JP7315486B2 - Ceramic bonded body, manufacturing method thereof, and charged particle beam accelerator - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a ceramic bonded body, a manufacturing method thereof, and a charged particle beam accelerator.

Conventionally, a beam duct with a large opening diameter is formed in a long shape by joining end faces of a plurality of ceramic ducts by a glass joining method. However, since beam ducts of proton accelerators are exposed to high-intensity radiation, glass joints tend to deteriorate due to radiation and deterioration over time, raising concerns that high airtightness cannot be maintained.

In order to solve such concerns, Patent Document 1 proposes a beam duct for an accelerator beam formed in a long shape by directly joining by brazing after metallizing the end faces of a plurality of ceramic ducts by a high-melting-point metal method.

Japanese Patent Application Laid-Open No. 2003-324000

When trying to use a sintered long ceramic duct as a beam duct, there is a problem that the inner wall surface undulates and warps in the direction perpendicular to the axial direction, making it impossible to set a wide trajectory range for charged particles.

The ceramic joined body of the present disclosure has an internal space for accelerating charged particles having a polygonal, racetrack-shaped, or circular cross-section perpendicular to the axial direction along the axial direction. surface is diffusion bonded.

Furthermore, in the method for manufacturing a ceramic bonded body of the present disclosure, when the first and second halves made of ceramics are provided with an inner space for accelerating charged particles and have a polygonal, racetrack-shaped, or ellipsoidal cross-section perpendicular to the axial direction, and the surfaces facing the first and second halves are arranged to face each other across the inner space, and the first and second halves are opposed to each other, the first and second halves are opposed to each other. 2. After the opposing surfaces are adsorbed, heat treatment is performed by pressing from the thickness direction.

The ceramic bonded body of the present disclosure can reduce undulation and warpage of the inner wall surface, and can set a wide trajectory range of charged particles.

1(a) is a perspective view and (b) is a cross-sectional view taken along line AA', showing an example of a ceramic bonded body of the present disclosure. FIG. 1. It is a part of the photograph which image|photographed the B section of the ceramic joined body shown in FIG. 1 with the scanning electron microscope. FIG. 2 is a schematic diagram showing a part of a cross section perpendicular to the axial direction X of the second half of the ceramic joined body shown in FIG. 1;

Hereinafter, the ceramic bonded body of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 shows an example of the ceramic bonded body of the present disclosure, (a) is a perspective view, and (b) is a cross-sectional view taken along line AA'.

The ceramic joined body 10 shown in FIG. 1 has an internal space S for accelerating charged particles, which has an octagonal cross section perpendicular to the axial direction X along the axial direction X, and is provided with a long first half 1 and a second half 2 made of ceramics, which are arranged opposite to each other with the internal space S interposed therebetween.

The first half 1 has a first inner bottom surface 1b forming the internal space S and a first inner surface 1c connected to the first inner bottom surface 1b, and the second half 2 has a second inner bottom surface 2b forming the internal space S and a second inner surface 2c connecting to the second inner bottom surface 2b.

Each dimension of the first half 1 and the second half 2 is, for example, length of 350 mm or more and 450 mm or less, thickness of 7 mm or more and 9 mm or less, and width of 60 mm or more and 65 mm or less.

The internal space S is surrounded by a first inner bottom surface 1b of the first half 1, a first inner surface 1c connected to the first inner bottom surface 1b, a second inner bottom surface 2b of the second half 2, and a second inner surface 2c connected to the second inner bottom surface 2b.

The internal space S in the cross section perpendicular to the axial direction X of the ceramic joined body 10 has an octagonal shape, but may have a polygonal shape other than the octagonal shape, a racetrack shape, or a circular shape. Note that the circular shape also includes an elliptical shape.

Both ends of the ceramic joint 10 are hermetically fixed to flanges (not shown) by sealing means, and charged particles supplied from one end of the ceramic joint 10 are discharged from the other end through the internal space S. The internal space S is kept in a high vacuum so as not to give resistance to charged particles. Accelerator bending electromagnets (not shown) are installed on the upper side of the first half 1 and the lower side of the second half 2 as accelerators for accelerating charged particles.

In the ceramic bonded body 10, when the surfaces facing the first half 1 and the second half 2 are the first facing surface 1a and the second facing surface 2a, respectively, the first facing surface 1a and the second facing surface 2a are diffusion-bonded. Here, the term "diffusion bonding" refers to a state of being bonded without a bonding layer made of glass or resin interposed therebetween. The waviness and warpage of the inner wall surfaces of the first half body 1 and the second half body 2 that occur along the direction perpendicular to the axial direction can be reduced by polishing before diffusion bonding. Therefore, when the waviness and warpage are reduced by polishing, the trajectory range of the charged particles can be set wide.

The shape of the internal space S in the cross section perpendicular to the axial direction X of the ceramic joined body 10 is preferably a flat polygonal shape, a racetrack shape, or an elliptical shape in which the short axis is located in the thickness direction and the long axis is located in the direction perpendicular to the thickness direction. When the shape of the internal space S is such a shape, the interval between the bending electromagnets for an accelerator installed on both sides in the thickness direction of the ceramic joined body 10 can be narrowed, so that the power supplied from the power supply to the bending electromagnets for an accelerator can be reduced, and the cost can be suppressed.

In particular, the arithmetic mean roughness Ra of at least one of the first opposing surface 1a and the second opposing surface 2a
is preferably 0.02 μm or more and 0.4 μm or less.

When the arithmetic mean roughness Ra is 0.02 μm or more, the anchoring effect is enhanced, so that the possibility that the first half 1 and the second half 2 are separated from each other is suppressed. On the other hand, when the arithmetic mean roughness Ra is 0.4 μm or less, the amount of foreign matter adhering to the first facing surface 1a and the second facing surface 2a is reduced, so high bonding strength can be maintained.

The cutting level difference Rδc, which represents the difference between the cutting level at a load length ratio of 25% in the roughness curve of at least one of the first opposing surface 1a and the second opposing surface 2a and the cutting level at a load length ratio of 75% in the roughness curve, is preferably 0.03 μm or more and 0.8 μm or less.

When the cutting level difference Rδc is 0.03 μm or more, the anchoring effect becomes higher, so that the possibility that the first half 1 and the second half 2 are separated from each other is further suppressed. On the other hand, when the cutting level difference Rδc is 0.8 μm or less, the amount of foreign matter adhering to the first opposing surface 1a and the second opposing surface 2a is reduced, so a high bonding strength can be maintained over a long period of time.

The arithmetic mean roughness Ra and the cutting level difference Rδc of the first opposing surface 1a and the second opposing surface 2a conform to JIS B 0601: 2001, and can be measured using a laser microscope (manufactured by Keyence Corporation, an ultra-deep color 3D shape measuring microscope (VK-X1000 or its successor model)). As the measurement conditions, there is no cutoff value λs, the cutoff value λc is 0.08 mm, the measurement range per location is 1404 μm × 1053 μm from the unbonded portion of the first opposing surface 1 a and the second opposing surface 2 a, and four lines to be measured may be drawn at approximately equal intervals along the longitudinal direction for each measurement range.

FIG. 2 is a part of a photograph taken with a scanning electron microscope of the B portion of the ceramic joined body shown in FIG.

As shown in FIG. 2 , part of the ceramic crystal grains 3 in the second half 2 may bite into the first half 1 . With such a configuration, part of the crystal grains 3 are responsible for preventing the separation from the first half 1, so the reliability is improved.

Similarly, part of the ceramic crystal grains in the first half 1 may bite into the second half 2 . With such a configuration, some of the crystal grains are responsible for preventing separation from the second half 2, so reliability is improved.

3 is a schematic diagram showing a part of a cross section perpendicular to the axial direction X of the second half of the ceramic joined body shown in FIG. 1. FIG.

As shown in FIG. 3, the height difference (L) between the peak of the maximum height of the ceramic crystal grains 3 located on at least one of the first opposing surface 1a and the second opposing surface 2a and the bottom of the lowest height of the ceramic crystal grains or the grain boundary phase 4 is preferably 0.08 μm or more and 1.6 μm or less.

When the height difference (L) is 0.08 μm or more, the anchoring effect becomes higher, so the risk of the first half 1 and the second half 2 separating from each other is further suppressed. On the other hand, when the difference in height (L) is 1.6 μm or less, the amount of foreign matter adhering to the first opposing surface 1a and the second opposing surface 2a is reduced, so high bonding strength can be maintained over a long period of time.

Note that reference numeral 5 shown in FIG. 3 denotes a gap 5 indicating an unbonded portion.

To measure the height difference (L), first, a cross section perpendicular to the axial direction X is ground with a copper disk using diamond abrasive grains having an average particle diameter _D50 of 3 μm. After that, it is polished with a tin plate using diamond abrasive grains having an average particle diameter _D50 of 0.5 μm. When the main component of the ceramics is aluminum oxide, the polished surface obtained by these polishing is heat-treated at 1480° C. until the crystal grains and the grain boundary layer become distinguishable, and a cross section is obtained as an observation surface. The heat treatment time is, for example, about 30 minutes. Then, using a scanning electron microscope, a cross section including at least one of the first opposing surface 1a and the second opposing surface 2a is photographed at a magnification of 6000 times. The height difference (L) shown in FIG. 3 can be measured in the 10 μm×15 μm field of view of the obtained photograph. The length to be measured is, for example, 30 μm.

At least one of the first inner bottom surface 1b, the first inner surface 1c, the second inner bottom surface 2b, and the second inner surface 2c is preferably either a ground surface or a polished surface.

At least one of the end surfaces 1d and 2d of the first half 1 and the second half 2 is preferably either a ground surface or a polished surface.

With such a configuration, the flatness of each surface, the arithmetic mean roughness Ra, the cutting level difference R[delta]c, etc. can be controlled within desired ranges, thereby improving the airtightness.

Next, an example of the manufacturing method of the ceramic bonded body of the present disclosure will be described.

When the main component of the ceramics is aluminum oxide, aluminum oxide powder (having a purity of 99.9% by mass or more), which is the main component, and powders of magnesium hydroxide, silicon oxide, and calcium carbonate are put into a grinding mill together with a solvent (ion-exchanged water). After pulverizing until the average particle size (D ₅₀ ) of the powder becomes 1.5 μm or less, an organic binder and a dispersant for dispersing the aluminum oxide powder are added and mixed to obtain a slurry.

Here, the content of magnesium hydroxide powder is 0.3 to 0.42% by mass, the content of silicon oxide powder is 0.5 to 0.8% by mass, the content of calcium carbonate powder is 0.060 to 0.1% by mass, and the balance is aluminum oxide powder and unavoidable impurities.

Organic binders include acrylic emulsion, polyvinyl alcohol, polyethylene glycol, polyethylene oxide and the like.

Next, after the slurry is spray granulated to obtain granules, a columnar molded body is obtained by applying a molding pressure of 78 MPa or more to 128 MPa or less using a uniaxial press molding device or a cold isostatic press molding device.

A long groove, which will become the internal space S after firing, is formed in this compact by cutting to obtain a first compact that is a precursor of the first half 1 and a second compact that is a precursor of the first half 2 .

Next, the first sintered body and the second sintered body are obtained by firing the first molded body and the second molded body at a firing temperature of 1500° C. or more and 1700° C. or less and a holding time of 4 hours or more and 6 hours or less.

Then, by subjecting the first inner bottom surface and the first inner surface of the first sintered body and the second inner bottom surface and the second inner surface of the second sintered body to at least one of grinding and polishing, the first half and the second half can be obtained, respectively.

Here, polishing may be performed using diamond abrasive grains having an average particle diameter _D50 of, for example, 2 μm or less, and water may be adhered (for example, sprayed with water droplets) to at least one of the first opposing surface and the second opposing surface. Adhered water can bring the first opposing surface and the second opposing surface into close contact with each other by surface tension, and elements other than Al (Si, Mg, Ca) induced by a hydration reaction (local hydrolysis reaction of OH groups by H ₂ O with a small amount of impurities) are recrystallized with aluminum oxide due to the difference in electronegativity, and a strong bond can be obtained.

Then, after the first opposing surface and the second opposing surface are adsorbed, they are pressed from the thickness direction and heat-treated, thereby obtaining the ceramic bonded body of the present disclosure having an inner space along the axial direction X and having a polygonal, racetrack-shaped or circular cross-section perpendicular to the axial direction X. The heat treatment temperature is, for example, 1000° C. or higher and 1800° C. or lower, preferably 1700° C. or higher and 1800° C. or lower, and the heat treatment time is, for example, 30 minutes or longer and 120 minutes or shorter. Further, the pressure required for pressing is not limited, and is appropriately set according to the size and material of the first half body 1 and the second half body 2, and the like. Specifically, it is preferable to press with a pressure of about 1 kgf to 5 kgf.

After joining, at least one of the end surfaces of the first half and the second half may be ground or polished, and such processing can improve the airtightness in the axial direction X.

Since the ceramic bonded body obtained by the above-described manufacturing method can set a wide trajectory range of charged particles, a charged particle beam accelerator equipped with this ceramic bonded body as a beam duct can increase the efficiency of supplying and discharging charged particles.

REFERENCE SIGNS LIST 10 ceramic bonded body 1 first half 2 second half 3 crystal grain 4 grain boundary phase 5 void

Claims (12)

Along the axial direction, it has an internal space for accelerating charged particles and has a polygonal, racetrack-shaped or circular cross-section perpendicular to the axial direction. , ceramic joints. 2. The ceramic joined body according to claim 1, wherein at least one of said first opposing surface and said second opposing surface has an arithmetic mean roughness Ra of 0.02 [mu]m or more and 0.4 [mu]m or less. The ceramic bonded body according to claim 1 or 2, wherein a cutting level difference Rδc, which represents a difference between a cutting level at a load length ratio of 25% on each roughness curve of the first opposing surface and the second opposing surface and a cutting level at a load length ratio of 75% on the roughness curve, is 0.03 µm or more and 0.8 µm or less. 4. The ceramic joined body according to claim 1, wherein a part of said ceramic crystal grains in said second half bites into said first half. 5. The ceramic joined body according to claim 1, wherein a part of said ceramic crystal grains in said first half bites into said second half. The ceramic bonded body according to any one of claims 1 to 5, wherein a height difference (L) between a peak of the maximum height of the ceramic crystal grains located on at least one of the first opposing surface and the second opposing surface and a bottom of the lowest height of the ceramic crystal grain or grain boundary phase is 0.08 μm or more and 1.6 μm or less. The first half has a first inner bottom surface that forms the internal space and a first inner surface that connects to the first inner bottom surface, and the second half has a second inner bottom surface that forms the internal space and a second inner surface that connects to the second inner bottom surface,
7. The ceramic joined body according to claim 1, wherein at least one of the first inner bottom surface, the first inner surface, the second inner bottom surface and the second inner surface is either a ground surface or a polished surface. 8. The ceramic joined body according to claim 1, wherein at least one of the end surfaces of said first half and said second half is either a ground surface or a polished surface. An elongated first half body and a second half body made of ceramics are provided along the axial direction and have a polygonal, racetrack-shaped, or circular cross-section perpendicular to the axial direction, and are arranged to face each other across the internal space. A method for manufacturing a ceramic bonded body, in which heat treatment is performed by pressing from a direction. 10. The method of manufacturing a ceramic bonded body according to claim 9, wherein said first opposing surface and said second opposing surface are polished. 11. The method for manufacturing a ceramic bonded body according to claim 9 or 10, wherein at least one of the end faces of the first half and the second half is pressed from the thickness direction, heat-treated and pressed, and then at least one of the end faces of the first half and the second half is ground or polished. A charged particle beam accelerator comprising the ceramic joint according to any one of claims 1 to 8 as a beam duct.

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